Add support to typescript

[ReyPena]

this will help for projects build on node.
It requires a module declaration on a .d.ts file.
something like: declare module 'busboy-body-parser'

[houssem-yahiaoui]

@ReyPena you can overcome the support by simply creating a new interface and adding the files as attribute there as Typescript have type declaration merging it will just give you a new type with files on.

interface RequestWithFiles extends Request {
    files: any
}

Hope this helps